A method of manufacturing a slide fastener by incorporating and fixing a continuous fastener element acquired by forming a monofilament made of synthetic resin along one side edge of a fastener tape simultaneously with weaving the fastener tape has been widely known. A representative example of the incorporated fastener element at this time includes a coil-shaped continuous fastener element and a zigzag-type continuous fastener element. The continuous fastener elements include engaging heads that engage with elements of opposing fastener stringers, connecting portion that connect adjacent elements, a pair of upper and lower leg portions that couple the engaging heads and the connecting portions, and they are, in advance, formed to be incorporated and sewn into the fastener tape or incorporated into the fastener tape while being formed during weaving.
However, the coil-shaped continuous fastener element is attached onto one surface of the fastener tape regardless by incorporating or sewing. As a result, in a case of the slide fastener, when the slide fastener is bent down with a side where the fastener element is placed facing up, the slide fastener is easily bent, but when the slide fastener is bent up, the slide fastener is difficult to bend. Meanwhile, when the slide fastener is intended to be bent down, disengagement of elements, that is, break in the engagement easily occurs.
Unlike this, in the slide fastener to which the zigzag-type continuous fastener element is attached, the element is attached to the fastener tape while the fastener tape is inserted into a continuous element row which is doubled back and connecting portions that connect two adjacent elements to each other are alternately exposed on front and back surfaces of the fastener tape and shapes thereof are front-back symmetrical to each other. Therefore, front and back are not clear by an appearance and a touch as the fastener stringer and further, even though the slide fastener is bent in a longitudinal direction of the tape while the elements engage with each other, there is no change in flexibility that the slide fastener is bent in front and back directions and the engagement breaking is not also likely to occur. However, in a general slide fastener in prior art, in which a zigzag-type continuous fastener element is incorporated simultaneously with weaving of a fastener tape, a weft yarn may be incorporated through a connecting portion that connects adjacent elements from outside and in this case, the weft yarn is easily cut because an inner surface of a slider is in slide contact with the weft yarn, and as a result, the slide fastener does not endure long use.
A slide fastener attached with the zigzag-type continuous fastener element to overcome the disadvantage is disclosed in, for example, JP 57-058922 B (Patent Document 1) and JP 02-177902 A (Patent Document 2). Among them, according to Patent Document 1, while the fastener tape is formed by double weaving for each element of the zigzag-type continuous fastener element, an upper tape part is woven so as to cover an upper surface with weft yarns and a plurality of warps disposed at an upper portion of an upper leg portion of a preceding element and a lower tape part is woven so as to cover a lower surface with weft yarns and a plurality of warps disposed at a lower portion of a lower leg portion of a subsequent element, and a fastener tape main body portion having one sheet of tape surface is woven by collecting the weft yarns on the tape surface of the fastener tape subsequent to a boundary of upper and lower connecting portions of the respective elements.
Further, according to the slide fastener attached with the zigzag-type continuous fastener element disclosed in Patent Document 2, the zigzag-type fastener element is incorporated, a base organization of an element attaching portion of the fastener tape is inserted between the upper and lower connecting portions of the zigzag-type fastener element, and warps of the base organization is used from the outside of upper and lower leg portions in order to fix the upper and lower leg portions of the zigzag-type fastener element. The fastener tape is woven by a needle weaving machine, and as a result, a weft yarn, which reciprocates in a preceding opening, reciprocates in a width direction of the tape to be weft-inserted in a subsequent opening and thereafter, is introduced into the subsequent opening and the process is repeated to perform weaving. According to Patent Document 2, the weft yarn reciprocates twice to be weft-inserted between adjacent fastener elements, that is, so called 2 pick is achieved between two adjacent fastener elements.